Supervisory system for telephone-lines.



PATENTED SEPT. 8, 1908, W- W- DEAN.

SUPERVISORY SYSTEM FOR TELEPHONE LINES. nruouronnnnp now. a1, 1903.

UNITED STATES PATENT OFFICE.

WILLIAM W. DEAN, OF CHICAGO, ILLINOIS, ASSIGNOR TO KELLOGG SWITCIIBOARDAND SUPPLY COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OP ILLINOIS.

SUPERVISORY SYSTEM FOR TELEPHONE-LINES.

Application filed October 31, 1903.

To all whom it may concern:

Be it known that I, WILLIAM W. DEAN, a citizen of the United States ofAmerica, and resident of Chicago, county of Cook, and State of Illinois,have invented a new and useful Improvement in Supervisory Systems for'lelephone-Lines, of which the following is a specification.

My invention relates to supervisory systems for telephone lines.

It is desirable in connecting subscribers lines for conversation, thatthe operator shall be enabled to entirely supervise each connection;that is, that she shall be informed at all times of the condition of thesubscribers telephones. The preferred form of signal for supervisorypurposes is a small incandescent lamp, which is adapted to be lightedwhenever a connection exists with .the telephone line and thesubscribers telephone is not in use, but is extinguished when thesubscribers telephone is in use. Thus when a connection is establishedwith an idle line, the signal lamp is lighted until the subscriberresponds, so that the operator is informed that the subscriber has notyet taken up his telephone. Upon the response of the subscriber the lampis extinguished, and the operator is informed that the subscriber hasresponded. When a conversation is terminated and the subscriber hangs uphis telephone, the lamp is lighted a second time and the operator isthus informed that the conversation has terminated, when the connectionis taken down and the lamp again extinguished. This control of the lampsis usually accomplished by supervisory relays associated with the cordcircuit employed to establish the connection. In one type of linecircuit known as the three-wire type, the said signal lamps are placedin third conductors connected with the cord circuits and an associatedrelay is placed-in one of the talking strands of the cord circuit tosuitably control the said lamp. In a second type of line, namely thetwo-wire type, only the two talking strands are employed in the cordcircuit, and hence a pair of relays is associated with each end of thecord circuit, one relay of the pair being used to place the lamp incondition to operate as soon as the cord circuit is connected with theline and the other being responsive to the current over the telephoneline and serving to render said signal inert whenever the subscriberstelephone is in use.

Specification of Letters Patent.

Patented Sept. 8, 1908.

Serial No. 179,265.

My invention is particularly adapted for use in connection with thelatter type of line, namely the two-wire type, and in connection withthe same I provide means for dispensing with the additional relay thatis employed to place the lamp in condition to operate upon the initialconnection of the cord circuit with the telephone line. In the formertype of line, that is the three wire type, repeating coils arepreferably used in the cord circuit with the middle points of theirwindings on each side connected directly to the central common battery.In the latter type of line, that is the tw'owire type, it is not commonto so employ repeating coils but condensers are utilized in each of thetalking strands to conductively separate but inductively unite the twoends of the same.

In my invention I make use of the repeating coil, the same as in thethree wire type, and at the same time the supervisory signals areindependently controlled by the two sub- 'scribers.

In carrying out my invention in one specific embodiment which has beenworked out for commercial purposes, I place the said signal in the pathof current over one of the talking strands of the cord circuit. I mayalso arrange to remove the resistance of the corresponding winding ofthe repeating coil from said strand, under normal conditions and toinsert said resistance and at the same time retire the signal lamp whenthe subscribers telephone is in use and current is flowing over thetelephone line. I prefer in thus carrying out my invention to place thelamp directly in one strand of the cord circuit and the controllingsupervisory relay in the opposite strand, the said relay being providedwith normally closed contacts which shunt the winding of the repeatingcoil that is in series with the said lamp, and the forward contacts ofsaid relay being adapted to close a shunt about the said lamp. henconnection is established with a line, therefore, the line being soarranged that a local path for current is completed over said talkingstrand including the signal lamp, the said lamp is lighted and thecorresponding winding of the repeating coil is out out of circuit; andwhen the subscriber responds the said winding is cut into circuit andthe lamp re moved.

My invention is illustrated in the accompanying drawing in which thefigure is a diagram of a telephone system embodying my improvements.

In said figure, L and L indicate subscribers lines extending in twolimbs 2 and 3 from their respective substations A and D to the centraloflice C. Each substation is provided with a signaling bell 4 and acondenser 5 in a bridge of said conductors that is 'normally closed bythe switch-hook 6, a trans mitter 7 and 'a receiver 8 together with aretardation coil 9 being adapted to be suitably included in circuit withsaid conductors when the receiver is removed from the said hook. Thisapparatus is intended merely to indicate any suitable or desired commonbattery outfit.

At the central oflice each line is provided with a line signal S, ananswering jack J, and multiple jacks such as J and J in any desirednumber. The line conductor 3 is normally connected with conductor 10including the winding of the line relay R and is con nected to thebattery lead 11 extending from the live pole of the central commonbattery B but when the cut-off relay R", which is legged to ground fromthe sleeve side of the jack section of the telephone line is energized,the said line conductor 3 is disconnected from said conductor 10 and isconnected with the sleeve side of said jack section. The line conductor2 is normally grounded through a spring of said cut-off relay R but isadapted to be disconnected from ground when a con-- nection isestablished with any ofthe said jacks and to be connected with the tipside thereof.

The operators outfit comprises a plurality of cord circuits of the typeshown in the drawing, each of which is provided with an answering plug Pand a calling plug P having tip and sleeve contacts adapted to registerwith the corresponding contacts of the spring jacks of the line. The tipcontact of the answering plug P is connected by a flexible conductivestrand t with the winding 'w of the repeating coil W, while thecorresponding contact of the calling plug is joined by a similar strandt with the associated winding w of said repeating coil. The sleevecontacts of said plugs are joined by the similar strands s and s withthe windings w" and w respectively, of said repeating coil, and theinner ends of said repeating coil windings are connected to the oppositepoles of thecentral common battery B, as shown, the positive pole ofsaid battery being also grounded as indicated in the drawing. Asupervisory lamp S associated with the answeringplug P is located in thestrand 8 of the cord circuit and is'suitably controlled by thesupervisory relay 1" placed in the opposite strand of said cord circuit.The branch conductors 12 and 13 are normally connected together throughthe back contacts of said supervisory relay 1" and serve when soconnected, to short circuit the winding w of the repeating coil. Aconductor 14 is adapted to be connected in shunt of the said lamp Stogether with the conductor 13 when the said supervisory relay isenergized. A similar supervisory signal S is associated with theanswering plug P and is controlled in the same manner by the supervisoryrelay 1, whose winding is connected in the opposite strand t of the cordcircuit. This relay serves to control through the branch conductors 15,16 and 17, the short circuits of both the repeating coil winding w andthe lamp S The operators telephone set includes the head receiver 18,the secondary of her induction coil 19 and a suitable condenser cadapted to be bridged across the calling end of the cord circuit bymeans of any suitable listening key, while her transmitter 20 and theprimary of her induction coil are charged from any suitable source ofcurrent and which may be the battery B. A ringing generator 21 isadapted to be connected by the ringing key 22 with the tip strand of thecord circuit, while the sleeve strand is simultaneously connectedthrough the branch 23 by the sleeve contact of said key with the batterylead 11.

In the operation of the invention the sub- 9 scriber at station A, forexample, takes up his receiver and thereby completes a path for currentfrom said battery B over conductors 11 and 10, including the winding ofthe line relay R, line conductor 3, through the substation devices andback through conductor 2 to ground. Current in this path sufiices toactuate the line relay R to cause it to close the local circuit of theline signal S thus lighting the same to attract the attention of theoperator, who upon seeing the signal inserts the answering plug P of hercord circuit in the answering jack J and depresses her listening key toconnect her receiver with the said cord circuit. The insertion of theplug P closes a path for current from the live pole of the battery Bover the sleeve strand 8 and the sleeve conductor of the jack section ofthe telephone line and through the winding of the cut-off relay R toground. This relay 115 is actuated to disconnect conductor 10 fromtheline conductor 3 and ground from line conductor 2, and to connectsaid conductors with the jack portion of the line. The winding w of therepeating coil W is at this time I short circuited by the conductors 12and 13 through the normal contacts of the supervisory relay 7 and theresistance of the cutoff relay R and the lamp S is such that the latterwould be lighted under these circumstances were it not for the fact thatthe subscribers telephone is ol'l' its hook, and therefore, as soon asthe cut-oil relay R is energized current is permitted to flow over themetallic line and through the supervisory relay 7" in its return to thegrounded pole of said battery. This relay 1 is therefore actuated andthe lamp S is prevented from lighting at this time. Upon learning theorder of the calling subscriber, the wanted line is tested in the usualmanner by touching the tip of the calling plug to one of thetest ringsof the multiple jacks of the line. It will be observed that said testrings are nor mally grounded through the winding of the cut-off relayand since the tip of the calling plug is likewise grounded through thewinding of the repeating coil no flow of current takes place when anidle line is tested, and no click is received by the operator, who isthus informed that the line is idle. If the line is engaged, however,said test rings are connected through the sleeve strand of the insertedcord circuit with the live pole of said battery B and hence theapplication of the ground tip of the plug to a test ring of the linecompletes a path for current from said battery through the tip strand ofthe testing cord and a click is received by the operator.

Assuming that the line is found idle, the calling plug is inserted andthe subscriber is called by depressing the ringing key. The operation ofthe ringing key provides a path for steady current from the battery B,through conductors 11 and Q3 to maintain the cut-off relay of the wantedline actuated during ringing.

After the subscriber has been called but before his response thesupervisory signal S is lighted, the resistance of the winding 10 of therepeating coil being cut out of circuit to increase the margin ofoperationa of said lamp and the operator is thus notified of thecondition of the called subscribers telephone. l/Vhen the subscriberresponds, the relay r is actuated and the lamp S is short circuited andretired, and the operator knows that the arties are in conversation. Atthe termination of the conversation, the return of the receivers totheir hooks deenergizes the relays r and r in the cord circuit andpermits said lamps S and S to glow, upon observing which the operatortakes down the connection and restores all parts to normal condition.The electrical dimensions of the various parts may be those ordinarilyemployed or such as are desired to accomplish the various resultssought.

While various modifications and arrangements may be made withoutdeparting from the spirit and scope of my invention, what I claim anddesire to secure by Letters Patent 1s:

1. In atelephone system, the combination with telephone lines, of a cordcircuit to establish connections for conversation with said lines, saidcord circuit having two strands included one in each side of the talkingcircuit, a non-inductive supervisory signal in one of the strands, and asupervisory relay in the opposite strand to deprive said signal ofoperating current, substantially as described.

2. In a telephone system, the combination with telephone lines, of acord circuit to establish connections therewith for conversation, arepeating coil and a source of current bridged across said cord circuit,a supervisory signal in the path of current over one strand of the cordcircuit, a supervisory relay in the opposite strand said relay servingto normally short circuit the winding of the repeating coil that is inseries with said signal, and during conversation to open the shortcircuit about said winding and to establish a second short circuit aboutthe said signal, substantially as described.

3. In a telephone system, the combination with a telephone line, of acord circuit for establishing connections therewith for conversation,said circuit having a strand included in each side of the talkingcircuit, a supervisory lamp in one of said strands and a supervisoryrelay in the other strand, said relay being adapted when operated tocomplete a shunt path about said lamp, substantially as described.

4. In a telephone system, the combination with a telephone line, of acord circuit to establish connections therewith for conversation, asupervisory signal and a resistance in the path of current over atalking strand of the cord circuit energized when a connection isestablished with the line, a supervisory relay associated with saidcircuit, energized over another strand thereof and operated duringconversation by current over the telephone line to place a shunt aroundsaid signal and thereby render it inert, substantially as described.

5. In a telephone system, the combination with a telephone line, of acord circuit to connect therewith for conversation, a source of currentfor the cord circuit, a resistance and a signal adapted to be placed ina circuit with said source when the cord is connected with a line, meansfor shunting said resistance when the line is open at the substation,whereby the signal receives sufficient current to display it and forshunting said signal when the line is closed at the substation, wherebythe signal is efiaced, substantially as described.

6. In a telephone system, the combination with a cord circuit, of asource of current associated therewith, a signaling device actuated bycurrent in one of the talking strands of said cord circuit, a relayactuated by current in another strand of said cord circuit, and means toshunt said signal to deprive the same of operating current by theactuation of said relay, substantially as described.

7. In a telephone system, the combination with a cord circuit, of asignaling device actuated by current in one of the talking strands ofsaid cord circuit, a relay actuated by current in another talking strandof said cord circuit, and means to shunt said signaling device tocomplete a path for battery current about said signal by the actuationof said relay, substantially as described.

8. In a telephone system, the combination with a telephone line, of acord circuit to connect therewith, a signaling device actuated bycurrent in a local circuit including a portion of one of the talkingstrands of the cord circuit, a relay actuated by current in the line andover a portion of another talking strand of the cord circuit, and meansto complete a path for battery current about said si naling device bythe actuation of said relay whereby said signaling device becomesinoperative, substantially as described.

9. In a telephone system, the combination with a telephone line, of acord circuit to connect therewith, a cut-off relay having its coilpermanently connected with one of the line contacts, a signaling deviceincluded in a talking strand of the cord circuit and adapted to bedisplayed by current through said cut oil relay, and means actuated bycurrent in the telephone line for closing a shunt about said signalingdevice, whereby it becomes in operative, substantially as described.

10. In a telephone system, the combina tion with a telephone line, of acord circuit adapted to be connected therewith for conversation, asource of current associated with the cord circuit and adapted tofurnish current to. the line over the limbs of the cord circuit, aresistance and a signal in the path of said current, means to shortcircuit the resistance when the cord is connected to a line open at thesubstation, whereby sufiicient with said resistance whereby the signallamp receives sufiicient current to actuate it, and means for removingsaid shunt and completing a shunt about the signal lamp, whereby thesignal becomes eflaced, substantially as described.

12. In a telephone system, the combina tion with a telephone line, of acord circuit to connect therewith for conversation, a source of currentassociated with the cord circuit and adapted to furnish energizationcurrent to the line when the cord is connected therewith, a resistanceand a signal in the path of such energizatio'n current, a relay for thecord circuit under the control of the subscriber during the connectionof the cord with the line, a normally closed shunt about said resistanceand a normally open shunt about said signal, said relay being adaptedwhen actuated to open the shunt about said resistance and to close theshunt about said sig nal, substantially as described.

Signed by me at Chicago, county of Cook, State of Illinois, this 29thday of October WILLIAM W. DEAN. l/Vitnesses:

GAZELLE BEDER, ROBERT LEWIS Arms.

